Mold for resin injection molding

Abstract

A mold for resin injection molding 1 having a shaping region formed by a low-density shaped portion 22 and a high-density shaped portion 21 in which each ventilation channel 32 for gas existing between an external region and a molding portion region forms a hollow state surrounded by a peripheral wall having any one or both of the high-density shaped portion 21 and the low-density shaped portion 22 , and the secondary vent 33 connecting communicatively with a region molding portion is formed only by a low-density shaped portion 22 with thickness thinner than that of the shaping region.

What is claimed is: 
     
       1. A mold for resin injection molding including a core shape mold and a cavity shape mold, each mold comprising:
 a shaping region with an inner wall and an outer wall formed by:
 a low-density shaped portion provided between the inner wall and the outer wall having a sintered density that allows gas discharging and sucking in with heating or cooling, and gas passing with resin blown, and 
 a high-density shaped portion having a sintered density that does not allow the gas to pass therethrough and surrounding the low-density shaped portion, 
 
 at least one primary vent connecting communicatively with an exterior of the mold, 
 at least one secondary vent connecting communicatively with a resin molding portion at an inside of the mold, each secondary vent being separate and distinct from and not directly connected with the low-density shaped portion of the shaping region, 
 at least one ventilation channel for gas, with each ventilation channel being formed between at least one said primary vent and at least one said secondary vent, with each ventilation channel communicating with both of at least one said primary vent and at least one said secondary vent, and each said ventilation channel forms a hollow state surrounded by a peripheral wall having at least one of the high-density shaped portion and the low-density shaped portion, and 
 wherein each secondary vent is formed only by the low-density shaped portion in a state of having a wall with thickness thinner than that of a remainder of the shaping region. 
 
     
     
       2. The mold for resin injection molding according to  claim 1 , in the core shape mold with a projection region inside of a peripheral wall, wherein each secondary vent is provided in at least one of:
 a gap between an inner wall portion and the projection region and 
 a gap between projection regions. 
 
     
     
       3. The mold for resin injection molding according to  claim 1 , in the cavity shape mold without a projection region inside of a peripheral wall, wherein each secondary vent is provided in a bottom portion surrounded by an inner wall portion. 
     
     
       4. The mold for resin injection molding according to  claim 1 , wherein a degree of a sintered density gradually changes in a boundary region between at least one high-density shaped portion and at least one low-density shaped portion. 
     
     
       5. The mold for resin injection molding according to  claim 1 , wherein each secondary vent has a thickness from 2 mm to 5 mm. 
     
     
       6. The mold for resin injection molding according to  claim 1 , wherein a region at the inside thereof is formed in a gradually thin state compared with a surrounding region. 
     
     
       7. The mold for resin injection molding according to  claim 6 , wherein an average thickness of each secondary vent is from 2 mm to 5 mm. 
     
     
       8. The mold for resin injection molding according to  claim 1 , wherein plural ventilation channels are set up for connecting communicatively with each primary vent and each secondary vent. 
     
     
       9. The mold for resin injection molding according to  claim 8 , wherein air pressures for blowing and suction are separately controlled according to respective ventilation channels. 
     
     
       10. The mold for resin injection molding according to  claim 1 , wherein the high-density shaped portion is provided between the inner wall and the outer wall.